The present invention relates to a rail support.
One of the problems associated with ballasted rail track is the formation of cavities in the ballast immediately underneath the rail track sleepers. This is a serious problem which, if not corrected, can result in deformation of the track and ultimately train derailment.
Current practice is to refill the cavity underneath each sleeper by tamping or xe2x80x9cstone-blowingxe2x80x9d. This is an extremely expensive process which has to be repeated at regular intervals.
The present invention seeks to provide an improved rail support.
The present invention provides a system for supporting a rail of a rail track above a substrate, the system including a support having an upper surface for supporting said rail and a lower surface facing said substrate, and means for maintaining support between said lower surface and said substrate in response to separation of said rail and said substrate and inhibiting movement of said rail towards said substrate.
In a preferred embodiment of a system according to the present invention, the system comprises a support for supporting road or rail vehicles above a prepared ground surface or formation, in the form of two or more parallel continuous beams or rails placed in the direction of travel of the vehicles and resting on and attached to cross members placed at right angles to the beams, the said cross members resting on a substrate comprising ballast or road pavement materials placed above the said prepared ground surface or formation, and the spaces between the said cross members being filled with granular material, the spacing and dimensions of the said cross members in section and the particle size of the said granular material being so selected that the said granular material may flow freely into any gaps which may form between the said cross members and the said ballast or road pavement materials, but not into the voids which are present within the said ballast or road pavement materials thus to compensate for uneven settlement of the said ballast or road pavement materials and to provide a self-levelling support system.
In a particularly preferred embodiment of a system according to the present invention, for use on ballast having a particle size of the order of 50 mm, the cross members have a width of between 120 mm and 290 mm, more preferably 150 mm, and a centre to centre spacing of between 400 mm and 700 mm, more preferably 550 mm. The particle size of the granular material placed between the cross members is preferably between 15 mm and 35 mm, more preferably 20 mm.
The present invention further provides a support for supporting a rail of a rail track above a substrate, the support having an upper surface for supporting said rail and a lower surface facing said substrate, and means for urging said upper and lower surfaces apart in response to separation of said rail and said substrate and inhibiting movement of said first and second surfaces towards one another, thereby to maintain support for said rail on said substrate.
In a preferred form of the invention, the support supports the rail or rails above the substrate between a pair of sleepers, the lower surface of the support bearing on the substrate. Alternatively, the support is placed under the sleeper.
In a further embodiment the support supports the rail or rails on a sleeper which is in turn supported on the substrate, the lower surface of the support bearing on the sleeper.
Advantageously, the support has resilient means biassed to allow movement of said upper and lower surfaces away from one another and to resist return movement of said upper and lower surfaces.
In a preferred embodiment of a support according to the present invention, which is particularly suitable for supporting a rail on a ballast substrate, the support is in the form of a container having an upper surface for supporting the said rail and a lower surface facing the said ballast and containing between the said upper and lower surfaces a suitable granular material which can flow freely as required through perforations in the said lower surface, thus allowing movement apart of said rail and ballast while inhibiting movement of said rail and said ballast towards one another, thereby to maintain support for said rail on said ballast.
In one form of this embodiment of the invention the container replaces the conventional sleeper and supports both rails. Alternatively, the conventional sleeper may be replaced by two containers one supporting each rail.
In a further embodiment the container supports a rail or rails above the ballast between a pair of conventional sleepers.
Advantageously means are provided for recharging the container with granular material as required and a tray is provided underneath the container to separate from the ballast any granular material which passes through the perforated lower surface of the container.